feat: Support SET NAMES literal [COLLATE literal]

[ovr]

Hello!

https://dev.mysql.com/doc/refman/8.0/en/set-names.html

SET NAMES {'charset_name'
    [COLLATE 'collation_name'] | DEFAULT}

Thanks

[coveralls]

Pull Request Test Coverage Report for Build 2817986477

• 40 of 43 (93.02%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 89.974%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/ast/mod.rs	10	13	76.92%

Totals
Change from base Build 2805421159:	0.02%
Covered Lines:	9136
Relevant Lines:	10154

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💛 - Coveralls

[alamb]

Awesome -- thank you @ovr